"Dave M" wrote in message
...

Nicads have historically been plagued by "dendrites", or crystals of
conductive material (probably cadmium, but not sure) between the
electrolyte layers in the cells. This creates a low resistance leakage
path inside the cells, rendering them incapable of retaining a charge
for any length of time or putting out their rated voltage. Dendrites are
responsible for the so-called "memory effect" that nicads are famous for.

There have been several procedures published on the net as to how to
remove dendrites (search for "nicad dendrites"). One process involves
charging a large electrolytic capacitor (eg, 500uF) to a few hundred volts,
discharging it through the bad cell, then running the cell through a couple
of charge/discharge cycles.

I assume the discharge is + to +.


I built a little box for this process several years ago, and it seems to
work.
It consists of a transformer, a voltage doubler, and a large capacitor.
A push-button switch triggers an SCR that lets the capacitor discharge into
the bad cell (sort of like a one-shot CD ignition).


I'll give this serious thought. The worst that can happen is that the battery
is ruined. (!!!) Thanks.

I'm still curious about the battery's unnaturally high voltage.